Precipitation, increase

It should, however, be noted that as the concentration of the excess of precipitant increases, so too does the ionic strength of the solution. This leads to a decrease in activity coefficient values with the result that to maintain the value of Ks more of the precipitate will dissolve. In other words there is a limit to the amount of precipitant which can be safely added in excess. Also, addition of excess precipitant may sometimes result in the formation of soluble complexes causing some precipitate to dissolve. 

Determination of copper as copper(I) thiocyanate Discussion. This is an excellent method, since most thiocyanates of other metals are soluble. Separation may thus be effected from bismuth, cadmium, arsenic, antimony, tin, iron, nickel, cobalt, manganese, and zinc. The addition of 2-3 g of tartaric acid is desirable for the prevention of hydrolysis when bismuth, antimony, or tin is present. Excessive amounts of ammonium salts or of the thiocyanate precipitant should be absent, as should also oxidising agents the solution should only be slightly acidic, since the solubility of the precipitate increases with decreasing pH. Lead, mercury, the precious metals, selenium, and tellurium interfere and contaminate the precipitate. 

Lead is toxic to all phyla of aquatic biota, but its toxic action is modified by species and physiological state, and by physical and chemical variables. Wong et al. (1978) stated that only soluble waterborne lead is toxic to aquatic biota, and that free cationic forms are more toxic than complexed forms. The biocidal properties of soluble lead are also modified significantly by water hardness as hardness increases, lead becomes less bioavailable because of precipitation increases (NRCC 1973). In salmonids, for example, the toxicity and fate of lead are influenced by the calcium status of the organism, and this relationship may account for the reduced effects of lead in hard or estuarine waters. In coho salmon (Oncorhynchus kisutch), an increase in waterborne or dietary calcium reduced uptake and retention of lead in skin and skeleton (Varanasi and Gmur 1978). 

In summary, these experiments demonstrate that Ba2 partitioning does not depend on the concentration of Ba2 over the broad range tested and that it is unaffected by moderate amounts of Sr2. Substantial quantities of NaCl decrease kcBa and rapid precipitation increases kcBa. These results suggest little or none of the Ba2 is incorporated in Ca 2 lattice sites in calcite, but instead adsorbs on surfaces and defects and is trapped by growth of the crystal. 

For precipitation the changes in the various regions differ in all seasons by only a few percent. On the northern side of the Alps, an increase of 8% is expected in winter (11% on the southern side) and a decrease of 17% in summer (19% on the southern side) by the middle of the twenty-first century. In spring and autumn, precipitation increases or decreases are possible. In summer, the area of uncertainty is particularly large. As for precipitation extremes model results indicate that heavy precipitation events of a kind that occur only every 8-20 years nowadays will on average occur every 5 years by the end of the century. The situation is less clear for the summer season. Although the models show a distinct decrease in the mean rainfall, the 5-yearly extreme value shows a slight increase. 

Because of decreased SO2 emissions, the importance of nitrogen for freshwater acidification becomes more and more determinant. Therefore, uncertainties in the evolution of nitrogen emissions make it difficult to predict future trends in freshwater recovery. On the other hand, climate warming may increase the number of alkaline rain episodes (containing Saharan dust) and enhance weathering reactions, which buffer better acid precipitation, increasing alkalinity and pH. 

Discontinuation of therapy Abrupt withdrawal of zonisamide in patients with epilepsy may precipitate increased seizure frequency or status epilepticus. Gradually reduce dose. 

Note Notice that the Hadley Centre Climate Model (HadCM2, heavy broken line) produces the most extreme precipitation increase the Canadian Climate Model (CGCM1, heavy black line) produces the second largest increase. 

If ammonium carbamate be treated with less than its eq. of calcium chloride, it soon gives a precipitate, and the filtered soln. gives no further precipitation when heated. The reaction is the same as when calcium chloride is added in excess. An ammoniacal soln. of calcium chloride gives an instantaneous but slight precipitate when treated with an excess of a soln. of ammonium carbamate. The precipitate increases slowly on standing, and next day, when boiled, the supernatant liquor gives a copious precipitate. The immediate precipitation is presumably due to the presence of ammonium carbonate, and the subsequent precipitation is due to the slow conversion of carbonate to carbamate in the presence of free ammonia. Hence, an ammoniacal soln. of calcium chloride gives an immediate precipitation with an excess of ammonium carbonate and a very slow precipitation with an excess of the carbamate. 

The glycosides of normal flavonoids (Table VII), except naringin, showed some precipitation alone, and without exception, precipitation increased considerably when they co-reacted with a few moles of phloroglucinol. The chalcones tended to precipitate more completely than the true flavonoids, probably because of the more free and reactive phloroglucinol moiety. 

Recently close attention has been given to assessment of climate in Siberia and the Far East as regions adjacent to the Arctic. Flere a 0.5°-0.9°C increase of temperature in the last decade was observed, the trends of average temperatures increasing from north to south. Precipitation was redistributed, with an increase in winter and a negligible decrease in some regions in summer. For instance, in the Amur River basin over the last 30 years precipitation in the cold period of the year increased by 35%, and annual precipitation increased by 12.3%. 

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